Many techniques have been developed in order to produce a high volume of electronic circuits at a rapid pace. One of these processes is generally referred to as solder reflow and involves heating a printed circuit board as a unitary structure to melt or reflow solder onto a number of electronic parts at one time.
More specifically, during the reflow soldering process a solder paste is applied at predetermined positions about a printed circuit board. These positions are determined by the placement of electronic parts on the board in relation to the metal runners or traces which have been printed on the board substrate. The solder paste is applied in a thin layer and is comprised of a mixture of solder material and a flux. Most often in soldering electronic parts the flux is a rosin-like material which acts to clean any oxides from the metal traces before the solder, allowing the solder to adhere to the metal trace.
After application of the solder paste, the electronic parts are surface mounted or inserted into fabricated holes in the circuit board. The printed circuit board is then passed through a soldering oven, commonly referred to as a reflow oven, where the printed circuit board and electronic parts are subjected to a temperature profile peaking at approximately 210 degrees Celsius. The peak oven temperature is dependent on the type of alloy being reflowed. Here, each position where the solder paste has been applied is melted allowing it to bond the electronic part to the metal trace of the printed circuit board.
A problem arises during the reflow process when specific portions of the electronic device which contain heat sensitive materials are subjected to such high temperatures. Often this in itself can cause a failure either to a semiconductor device or other parts such as connectors or the like. These parts include materials which were never intended to be subjected to such high temperature but are being used in this manner to facilitate a rapid production rate using the solder reflow process.
Thus, the need exists to provide a method of controlling temperature of the electronic part during the solder reflow process to prevent damage and/or failure to electronic parts or devices, yet allow solder reflow temperatures to exist at solder joint areas.